From: Oliver Neukum <oneukum@suse.de>
Date: Tue, 6 Aug 2013 12:22:59 +0000 (+0200)
Subject: USB: cdc-wdm: fix race between interrupt handler and tasklet
X-Git-Tag: v3.0.97~17
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fe3efa501f32fc05483a095334573799a954d1ab;p=thirdparty%2Fkernel%2Fstable.git

USB: cdc-wdm: fix race between interrupt handler and tasklet

commit 6dd433e6cf2475ce8abec1b467720858c24450eb upstream.

Both could want to submit the same URB. Some checks of the flag
intended to prevent that were missing.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c
index c84b455320885..0b85e2c7c3dda 100644
--- a/drivers/usb/class/cdc-wdm.c
+++ b/drivers/usb/class/cdc-wdm.c
@@ -171,6 +171,7 @@ skip_error:
 static void wdm_int_callback(struct urb *urb)
 {
 	int rv = 0;
+	int responding;
 	int status = urb->status;
 	struct wdm_device *desc;
 	struct usb_ctrlrequest *req;
@@ -244,8 +245,8 @@ static void wdm_int_callback(struct urb *urb)
 	desc->response->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
 	spin_lock(&desc->iuspin);
 	clear_bit(WDM_READ, &desc->flags);
-	set_bit(WDM_RESPONDING, &desc->flags);
-	if (!test_bit(WDM_DISCONNECTING, &desc->flags)
+	responding = test_and_set_bit(WDM_RESPONDING, &desc->flags);
+	if (!responding && !test_bit(WDM_DISCONNECTING, &desc->flags)
 		&& !test_bit(WDM_SUSPENDING, &desc->flags)) {
 		rv = usb_submit_urb(desc->response, GFP_ATOMIC);
 		dev_dbg(&desc->intf->dev, "%s: usb_submit_urb %d",
@@ -635,16 +636,20 @@ static void wdm_rxwork(struct work_struct *work)
 {
 	struct wdm_device *desc = container_of(work, struct wdm_device, rxwork);
 	unsigned long flags;
-	int rv;
+	int rv = 0;
+	int responding;
 
 	spin_lock_irqsave(&desc->iuspin, flags);
 	if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
 		spin_unlock_irqrestore(&desc->iuspin, flags);
 	} else {
+		responding = test_and_set_bit(WDM_RESPONDING, &desc->flags);
 		spin_unlock_irqrestore(&desc->iuspin, flags);
-		rv = usb_submit_urb(desc->response, GFP_KERNEL);
+		if (!responding)
+			rv = usb_submit_urb(desc->response, GFP_KERNEL);
 		if (rv < 0 && rv != -EPERM) {
 			spin_lock_irqsave(&desc->iuspin, flags);
+			clear_bit(WDM_RESPONDING, &desc->flags);
 			if (!test_bit(WDM_DISCONNECTING, &desc->flags))
 				schedule_work(&desc->rxwork);
 			spin_unlock_irqrestore(&desc->iuspin, flags);